Methods of using substantially hydrated cement particulates in subterranean applications

ABSTRACT

Methods of gravel packing comprising providing a gravel packing fluid comprising a base fluid and substantially hydrated cement particulates, introducing the gravel packing fluid into a subterranean formation, and depositing at least a portion of the substantially hydrated cement particulates in the subterranean formation to form a gravel pack. Gravel packing fluids that comprise a base fluid, and gravel comprising substantially hydrated cement particulates. Methods of gravel packing and fracturing a subterranean formation comprising fracturing the subterranean formation so as to create or enhance one or more fractures in the subterranean formation; introducing a fluid comprising a base fluid and substantially hydrated cement particulates through a well bore into the one or more fractures; and depositing at least a portion of the substantially hydrated cement particulates in the one or more fractures in the subterranean formation and in the well bore to form a gravel pack.

CROSS REFERENCE TO RELATED APPLICATION

This patent application is a Divisional of U.S. patent application Ser.No. 11/388,644, filed Mar. 24, 2006 now U.S. Pat. No. 7,341,104, whichis a Continuation-In-Part of U.S. patent application Ser. No.10/775,348, filed Feb. 10, 2004, now U.S. Pat. No. 7,086,466, eachdisclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

The present invention relates to substantially hydrated cementparticulates. More particularly, the present invention relates tosubterranean treatment fluids comprising substantially hydrated cementparticulates and associated methods of use in subterranean applications.

Hydraulic fracturing is a process commonly used to increase the flow ofdesirable fluids, such as oil and gas, from a portion of a subterraneanformation. Hydraulic fracturing operations generally involve introducinga fracturing fluid into a subterranean formation at or above a pressuresufficient to create or enhance one or more fractures in the formation.Enhancing a fracture includes enlarging a pre-existing fracture in theformation. The fracturing fluid may comprise particulates, oftenreferred to as “proppant” that are deposited in the fractures. Theproppant functions to prevent the fractures from fully closing upon therelease of pressure, forming conductive channels through which fluidsmay flow to (or from) the well bore.

Another process that involves the use of particulates is gravel packing.A “gravel pack” is a term commonly used to refer to a volume ofparticulate materials (such as sand) placed into a well bore to at leastpartially reduce the migration of unconsolidated formation particulatesinto the well bore. Gravel packing operations commonly involve placing agravel pack screen in the well bore neighboring a desired portion of thesubterranean formation, and packing the surrounding annulus between thescreen and the subterranean formation with particulate materials thatare sized to prevent and inhibit the passage of formation solids throughthe gravel pack with produced fluids. In some instances, a screenlessgravel packing operation may be performed.

Conventional particulates included as proppant and/or gravel insubterranean treatment fluids include, but are not limited to: sand;bauxite; ceramic materials; glass materials; polymer materials; Teflon®materials; nut shell pieces; seed shell pieces; fruit pit pieces; wood;composite particulates; cured resinous particulates comprising nut shellpieces, seed shell pieces, inorganic fillers, and/or fruit pit pieces;and combinations thereof. Conventionally, composite particulates thatmay be used comprise a binder and a filler material wherein suitablefiller materials include silica, alumina, fumed carbon, carbon black,graphite, mica, titanium dioxide, meta-silicate, calcium silicate,kaolin, talc, zirconia, boron, fly ash, hollow glass microspheres, solidglass, and combinations thereof. Sand is a common particulate utilizedin subterranean treatment fluids as either proppant or gravel, but theremay be issues related to supply and cost associated with using sand.

To modify one or more properties of a subterranean treatment fluid,various admixtures may be included in the subterranean treatment fluid.As used herein, the term “admixture” refers to materials, other than thebase fluid used for making the subterranean treatment fluid, which maybe added to the subterranean treatment fluid before or during itsmixing. Admixtures oftentimes are provided in the form of liquids orsoluble solids (e.g., powders). Attempts have been made to counteractthe problems that may be associated with the delivery of admixtures insolid and liquid form. For instance, an admixture provided in powderedform may become dry compacted, or the admixture, in another instance,may be coated onto a carrier particle. However, improvements are neededfor the delivery of admixtures into subterranean treatment fluids.

SUMMARY

The present invention relates to substantially hydrated cementparticulates. More particularly, the present invention relates tosubterranean treatment fluids comprising substantially hydrated cementparticulates and associated methods of use in subterranean applications.

An embodiment of the present invention provides a method of fracturing asubterranean formation that comprises fracturing the subterraneanformation so as to create or enhance one or more fractures in thesubterranean formation; introducing a fracturing fluid comprising a basefluid and substantially hydrated cement particulates into the one ormore fractures; and depositing at least a portion of the substantiallyhydrated cement particulates in the one or more fractures in thesubterranean formation.

Another embodiment of the present invention provides a method of gravelpacking that comprises providing a gravel packing fluid comprising abase fluid and substantially hydrated cement particulates, introducingthe gravel packing fluid into a subterranean formation, and depositingat least a portion of the substantially hydrated cement particulates inthe subterranean formation so as to form a gravel pack.

The features and advantages of the present invention will be readilyapparent to those skilled in the art upon a reading of the descriptionof the example embodiments, which follows.

DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention relates to substantially hydrated cementparticulates. More particularly, the present invention relates tosubterranean treatment fluids comprising substantially hydrated cementparticulates and associated methods of use in subterranean applications.While the substantially hydrated cement particulates of the presentinvention are useful in a variety of applications, they may beparticularly useful when included in fracturing fluids as proppant or ingravel packing fluids as gravel.

The subterranean treatment fluids of the present invention generallycomprise a base fluid and substantially hydrated cement particulates. Insome embodiments, the substantially hydrated cement particulates maycomprise an admixture. The substantially hydrated cement particulatesmay be included in the subterranean treatment fluid as proppant, gravel,lost circulation materials, carriers for admixtures, or combinationsthereof.

The base fluids utilized in the subterranean treatment fluids of thepresent invention can be any fluid suitable for use as a base fluid infracturing or gravel packing operations. Suitable base fluids include,but are not limited to, water, aqueous gels, viscoelastic surfactantgels, oil gels, gases, liquefied gases, liquefied hyrdocarbons,emulsions, and combinations thereof. Suitable aqueous gels are generallycomprised of water and one or more gelling or viscosifying agents.Optionally, the aqueous gel further may comprise a crosslinking agentfor crosslinking the gelling agent and further increasing the viscosityof the fluid. Suitable viscoelastic surfactant gels may comprise aviscoelastic surfactant and water. Suitable emulsions can be comprisedof two immiscible liquids such as an aqueous liquid or gelled liquid anda hydrocarbon. Suitable water used in the base fluids can be freshwater, salt water (e.g., water containing one or more salts dissolvedtherein), brine (e.g., saturated salt water), seawater, or any otheraqueous liquid that does not adversely affect other components in thesubterranean treatment fluid. The base fluid may also be foamed orunfoamed as desired for a particular application and may include, forexample, air, carbon dioxide, and/or nitrogen.

The subterranean treatment fluids of the present invention furthercomprise substantially hydrated cement particulates. The substantiallyhydrated cement particulates may be formed in any suitable manner. Incertain embodiments of the present invention, the substantially hydratedcement particulates present in the subterranean treatment fluids of thepresent invention are formed by providing a settable compositioncomprising a hydraulic cementitious material and water; allowing thesettable composition to set into a substantially hydrated mass; andcomminuting the substantially hydrated mass into smaller particles so asto form the substantially hydrated cement particulates used in themethods of the present invention. In another embodiment, the settablecomposition further may comprise an admixture. By including an admixturein the settable composition, the substantially hydrated cementparticulates formed using this settable composition should comprise theadmixture. In another embodiment, after comminution of the substantiallyhydrated mass into the substantially hydrated cement particulates, thesubstantially hydrated cement particulates may be coated with at leastone admixture. This permits the combination of admixtures that may notbe compatible when used in solution. An example method for producing thesubstantially hydrated cement particulates and/or intermixing theadmixtures therein is described in U.S. Pat. No. 6,648,962, thedisclosure of which is incorporated herein by reference.

Comminution of the substantially hydrated mass to form the substantiallyhydrated cement particulates may be accomplished by any of a variety ofsuitable methods. For example, comminution may be achieved by subjectingthe substantially hydrated mass to compressive or grinding forces, suchas by using a jaw crusher, a roller crusher (e.g., opposed steelrollers), a ball mill, a disk mill, or a grinder. After comminution, thesubstantially hydrated cement particulates may be highly granulate witha high surface area, thereby providing a high loading surface.

The size of the substantially hydrated cement particulates may varybased upon the desired application. In certain embodiments, thesubstantially hydrated cement particulates may have an average diameterin the range of from about 5 micrometers to about 2.5 millimeters.However, it should be understood that, in other embodiments, thesubstantially hydrated cement particulates may have an average diameterof greater than about 2.5 millimeters or of less than about 5micrometers as desired. One of ordinary skill in the art with thebenefit of this disclosure will know the appropriate size ofparticulates for a particular application.

Generally, the hydraulic cementitious material used to form thesubstantially hydrated cement particulates may be any hydrauliccementitious material that is suitable for use in cementing operations.A variety of hydraulic cementitious materials are suitable for use,including those comprised of calcium, aluminum, silicon, oxygen, and/orsulfur, which set and harden by reaction with water. Such hydrauliccementitious materials include, but are not limited to, Portlandcements, pozzolanic cements, gypsum cements, soil cements, calciumphosphate cements, high-alumina content cements, silica cements,high-alkalinity cements, slag cements, cement kiln dust, or mixturesthereof. “Cement kiln dust,” as that term is used herein, refers to apartially calcined kiln feed which is typically removed from the gasstream and collected in a dust collector during the manufacture ofcement. The chemical analysis of cement kiln dust from various cementmanufactures varies depending on a number of factors, including theparticular kiln feed, the efficiencies of the cement productionoperation, and the associated dust collection systems. Cement kiln dustgenerally may comprise a variety of oxides, such as SiO₂, Al₂O₃, Fe₂O₃,CaO, MgO, SO₃, Na₂O, and K₂O.

Vitrified shale also may be used to form the substantially hydratedcement particulates. Among other things, in some embodiments, vitrifiedshale may be included in the settable compositions used to form thesubstantially hydrated cement particulates. Such vitrified shale mayreact with lime present in, or added to, the settable composition toform a suitable cementing material, for example, calcium silicatehydrate. A variety of vitrified shales are suitable, including thosecomprising silicon, aluminum, calcium, and/or magnesium. Suitableexamples of vitrified shale include, but are not limited to,PRESSUR-SEAL® FINE LCM material and PRESSUR-SEAL® COARSE LCM material,which are commercially available from TXI Energy Services, Inc.,Houston, Tex.

The water utilized to form the substantially hydrated cementparticulates can be fresh water, salt water (e.g., water containing oneor more salts dissolved therein), brine (e.g., saturated salt water), orseawater. Generally, the water can be from any source, provided that itdoes not adversely affect other components in the settable composition.The water may be present in an amount sufficient to form a pumpableslurry. In certain exemplary embodiments, the water is present in thesettable compositions of the present invention in an amount in the rangeof from about 30% to about 180% by weight of the hydraulic cementitiousmaterial. In certain embodiments, the water may be added to thehydraulic cementitious material, admixture(s), or both. In anotherembodiment, the water may be incorporated in an aqueous dispersion,emulsion, or solution containing the admixture(s).

In certain embodiments of the present invention, the substantiallyhydrated cement particulates further may comprise a zeolite. Zeolitesgenerally are porous alumino-silicate minerals that may be either anatural or synthetic material. Synthetic zeolites are based on the sametype of structural cell as natural zeolites, and may comprisealuminosilicate hydrates. As used herein, the term “zeolite” refers toall natural and synthetic forms of zeolite.

In certain embodiments of the present invention, the substantiallyhydrated cement particulates further may comprise an admixture. Amongother things, this provides for the delivery of admixture(s) into asubterranean treatment fluid, for example, when the substantiallyhydrated cement particulates comprising an admixture are added to asettable composition. The admixture(s) may be provided as soluble solids(e.g., powders) or liquids. Any admixture commonly used in fracturing orgravel packing fluids may be included in the settable compositions. Awide variety of admixtures may be included in the subterranean treatmentfluid, including, but not limited to, fluid loss control additives,surfactants, salts, defoamers, formation conditioning agents, expandingadditives, flow enhancing additives, acids, corrosion inhibitors,breakers, crosslinking agents, viscoelastic surfactants, frictionreducers, gelling agents, biocides, algicides, combinations thereof, andthe like. One skilled in the art with the benefit of this disclosurewill know the type of admixture to include for a particular application.

In certain embodiments of the present invention, after comminution ofthe substantially hydrated mass into the substantially hydrated cementparticulates, the substantially hydrated cement particulates may becoated with at least one admixture. The coating of the admixture(s) ontothe substantially hydrated cement particulates may be applied using anysuitable coating method.

The amount of admixture or admixtures to include in the settablecompositions, coat onto the substantially hydrated cement particulates,or both, should depend, inter alia, on the desired amount of theadmixture(s) to incorporate into the subterranean treatment fluid. Thedesired amount of the admixture(s) to incorporate into the subterraneantreatment fluid may depend, inter alia, on the type of admixture(s)employed. Generally, the admixture(s) may be included in the settablecomposition in an admixture(s)-to-hydraulic cementitious material weightratio in the range of from about 5:95 to about 95:5. One of ordinaryskill in the art with the benefit of this disclosure will know theappropriate amount of the admixture(s) to include in the settablecomposition for a particular application.

Among other things, the methods of the present invention may provide forthe accurate measurement of the amount of the admixture(s) added tosubterranean treatment fluids as well as avoiding time-consuming labor,energy costs, and processing complexity that may be associated withconventional methods for the delivery of admixtures into subterraneantreatment fluids. An accurate measurement of the amount of admixture(s)in the subterranean treatment fluid may be obtained whether theadmixture(s) is added to a settable composition, coated onto thesubstantially hydrated cement particulates, or both. For example, theamount of the admixture(s) introduced into the subterranean treatmentfluid may be obtained by measuring the bulk weight of the substantiallyhydrated cement particulates and the relative amount of admixtures.

Typically, the substantially hydrated cement particulates may beincluded in a subterranean treatment fluid of the present invention inan amount sufficient for a particular application. In some embodiments,the substantially hydrated cement particulates are present in an amountup to about 30 pounds per gallon (ppg). In some embodiments, thesubstantially hydrated cement particulates are present in an amount upto about 23 ppg. In some embodiments, the substantially hydrated cementparticulates are present in an amount up to about 12 ppg. One ofordinary skill in the art, with the benefit of this disclosure, willrecognize the appropriate substantially hydrated cement particulatesconcentration of the subterranean treatment fluids for a chosenapplication.

Furthermore, additional additives may be added to the subterraneantreatment fluids of the present invention as deemed appropriate by oneskilled in the art. Examples of such additives include, but are notlimited to, fluid loss control additives, lost circulation materials,surfactants, salts, formation conditioning agents, defoamers, acids,corrosion inhibitors, breakers, biocides, algicides, crosslinkingagents, gelling agents, viscoelastic surfactants, friction reducers,expanding additives, flow enhancing additives, combinations thereof, andthe like.

In one embodiment, the present invention provides a method of using afracturing fluid in a subterranean formation comprising: fracturing thesubterranean formation so as to create or enhance one or more fracturesin the subterranean formation; introducing a fracturing fluid comprisinga base fluid and substantially hydrated cement particulates into the oneor more fractures; and depositing at least a portion of thesubstantially hydrated cement particulates in the one or more fracturesin the subterranean formation. The substantially hydrated cementparticulates deposited in the one or more fractures should prop thefractures so as to prevent them from fully closing. In some embodiments,hydrocarbons may be produced from the subterranean formation through theone or more fractures.

In one embodiment, the present invention provides a method of gravelpacking comprising: providing a gravel packing fluid comprising a basefluid and substantially hydrated cement particulates; introducing thegravel packing fluid into a subterranean formation; and depositing atleast a portion of the substantially hydrated cement particulates in thesubterranean formation so as to form a gravel pack. In some embodimentthe gravel packing fluid may be introduced into an annulus between ascreen and the subterranean formation. In some embodiments, hydrocarbonsmay be produced from the subterranean formation through the gravel pack.

Therefore, the present invention is well adapted to carry out theobjects and attain the ends and advantages mentioned as well as thosewhich are inherent therein. While numerous changes may be made by thoseskilled in the art, such changes are encompassed within the spirit ofthis invention as defined by the appended claims.

1. A method of gravel packing comprising: providing a gravel packingfluid comprising a base fluid and substantially hydrated cementparticulates; introducing the gravel packing fluid into a subterraneanformation; and depositing at least a portion of the substantiallyhydrated cement particulates into the subterranean formation to form agravel pack.
 2. The method of claim 1 wherein the base fluid is selectedfrom the group consisting of water, an aqueous gel, a viscoelasticsurfactant gel, an oil gel, a gas, a liquefied gas, a liquefiedhydrocarbon, an emulsion, and combinations thereof.
 3. The method ofclaim 1 wherein the substantially hydrated cement particulates comprisesan admixture.
 4. The method of claim 3 wherein the admixture comprisesat least one material selected from the group consisting of a fluid losscontrol additive, a surfactant, a salt, a defoamer, a formationconditioning agent, an expanding additive, a flow enhancing additive, anacid, a corrosion inhibitor, a crosslinking agent, a breaker, aviscoelastic surfactant, a friction reducer, a gelling agent, a biocide,an algicide, and combinations thereof.
 5. The method of claim 3 whereinthe substantially hydrated cement particulates are coated with at leastone additional admixture.
 6. The method of claim 1 wherein thesubstantially hydrated cement particulates comprises at least materialselected from the group consisting of Portland cement, a pozzolaniccement, a gypsum cement, a soil cement, a calcium phosphate cement, ahigh-alumina content cement, a silica cement, a high-alkalinity cement,a slag cement, cement kiln dust, a zeolite, vitrified shale, andmixtures thereof.
 7. The method of claim 1 wherein the substantiallyhydrated cement particulates are coated with at least one admixture. 8.The method of claim 1 further comprising the steps of: providing asettable composition comprising a hydraulic cementitious material andwater; allowing the settable composition to set into a substantiallyhydrated mass; and comminuting the substantially hydrated mass intosmaller particles so as to form the substantially hydrated cementparticulates.
 9. The method of claim 1 wherein the substantiallyhydrated cement particulates have an average particle diameter in therange of from about 5 micrometers to about 2.5 millimeters.
 10. Themethod of claim 1 wherein the substantially hydrated cement particulatesare present in the gravel packing fluid in an amount up to about 30pounds per gallon of the gravel packing fluid.
 11. The method of claim 1wherein the gravel packing fluid is foamed.
 12. The method of claim 1wherein the gravel packing fluid is introduced into an annulus between ascreen and the subterranean formation.
 13. The method of claim 1 furthercomprising the step of producing hydrocarbons from the subterraneanformation through the gravel pack.
 14. A method of gravel packingcomprising: providing a gravel packing fluid comprising a base fluid andsubstantially hydrated cement particulates, wherein the substantiallyhydrated cement particulates have an average particle diameter in therange of from about 5 micrometers to about 2.5 millimeters and whereinthe substantially hydrated cement particulates are present in the gravelpacking fluid in an amount up to about 30 pounds per gallon of thegravel packing fluid; introducing the gravel packing fluid into asubterranean formation; and depositing at least a portion of thesubstantially hydrated cement particulates into the subterraneanformation to form a gravel pack.
 15. The method of claim 14 wherein thebase fluid is selected from the group consisting of water, an aqueousgel, a viscoelastic surfactant gel, an oil gel, a gas, a liquefied gas,a liquefied hydrocarbon, an emulsion, and combinations thereof.
 16. Themethod of claim 14 wherein the substantially hydrated cementparticulates comprises an admixture.
 17. The method of claim 16 whereinthe admixture comprises at least one material selected from the groupconsisting of a fluid loss control additive, a surfactant, a salt, adefoamer, a formation conditioning agent, an expanding additive, a flowenhancing additive, an acid, a corrosion inhibitor, a crosslinkingagent, a breaker, a viscoelastic surfactant, a friction reducer, agelling agent, a biocide, an algicide, and combinations thereof.
 18. Themethod of claim 16 wherein the substantially hydrated cementparticulates are coated with at least one additional admixture.
 19. Themethod of claim 14 wherein the substantially hydrated cementparticulates comprises at least material selected from the groupconsisting of Portland cement, a pozzolanic cement, a gypsum cement, asoil cement, a calcium phosphate cement, a high-alumina content cement,a silica cement, a high-alkalinity cement, a slag cement, cement kilndust, a zeolite, vitrified shale, and mixtures thereof.
 20. The methodof claim 14 wherein the substantially hydrated cement particulates arecoated with at least one admixture.
 21. The method of claim 14 furthercomprising the steps of: providing a settable composition comprising ahydraulic cementitious material and water; allowing the settablecomposition to set into a substantially hydrated mass; and comminutingthe substantially hydrated mass into smaller particles so as to form thesubstantially hydrated cement particulates.
 22. The method of claim 14wherein the gravel packing fluid is foamed.
 23. The method of claim 14wherein the gravel packing fluid is introduced into an annulus between ascreen and the subterranean formation.
 24. The method of claim 14further comprising the step of producing hydrocarbons from thesubterranean formation through the gravel pack.